Performance enhancement of blue light-emitting diodes without an electron-blocking layer by using special designed p-type doped InGaN barriers

Zhang, Yunyan; Fan, Guanghan; Yin, Yongsheng; Yao, Guang-Rui

doi:10.1364/oe.20.00a133

Cited by 24 publications

(13 citation statements)

References 28 publications

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“…In addition, the strong polarization effects of the WZ nitride material can induce strong internal electrostatic fields (>1 MV cm −1 ) in the InGaN wells [342][343][344]. The fields can spatially separate the electron and hole wave functions, leading to low radiative recombination efficiency [337,345,346]. Therefore, the efficiency of the nitride LED is good at the blue wavelength region and drops dramatically at the long wavelength region [342].…”

Section: Light Emittersmentioning

confidence: 99%

“…This allows growing thick (tens of nanometre) and high-quality InGaN active region with low internal electrostatic fields, which can cover the full visible wave range. This is in stark contrast to the thin film nitride LEDs, whose QW thickness is normally limited to 2-4 nm [346,347]. The InGaN/GaN NW LEDs emitting from blue to red have been demonstrated [348,349].…”

Section: Light Emittersmentioning

confidence: 99%

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Elongated nanostructures for radial junction solar cells

et al. 2013

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In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

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Section: Light Emittersmentioning

confidence: 99%

Section: Light Emittersmentioning

confidence: 99%

Elongated nanostructures for radial junction solar cells

et al. 2013

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“…Nanowires (NWs) with a one-dimensional (1D) columnar shape at nanometer scale can lead to different crystallographic, photonic, electrical, and mechanical properties than those of their thin film counterparts. [1][2][3][4][5][6][7] These advantages can give new theories for device structure design. 8,9 For example, the nanoscale cross-section can efficiently relax strain without degrading the crystal quality of NWs.…”

Section: Introductionmentioning

confidence: 99%

Influence of droplet size on the growth of high-quality self-catalyzed GaAsP nanowires

et al. 2017

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Nanowires (NWs) have better functionality and superior performance as compared with the traditional thin film counterparts. However, NW growth is highly complicated and the growth mechanism is far from clear, especially when it is grown by vapor-liquid-solid mode. In this work, the influences of droplet size on the growth of self-catalyzed ternary NWs were studied using GaAsP NWs. The size-induced Gibbs−Thomson (GT) effect is observed for the first time in the self-catalyzed growth mode, which can make the smaller catalytic droplets have lower effective supersaturations. Thus, the droplet size can significantly influence the uniformity and composition of NWs. By carefully control the droplet size, the growth of highly uniform NW arrays are demonstrated. These results provide useful information for understanding the mechanisms of self-catalyzed III−V NW nucleation and growth with the important ternary III−V material systems.

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“…However, when the bandgap of the EBL increases, the polarization-induced charge increases as well. This in turn creates band bending in the EBL and lowers the blocking effect [9]. For this reason, the polarization of the EBL must be carefully considered and calibrated to achieve the best performance.…”

Section: Introductionmentioning

confidence: 99%

Design of electron blocking layers for improving internal quantum efficiency of InGaN/AlGaN-based ultraviolet light-emitting diodes

Park

Kim

2015

Appl. Phys. A

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In this paper, we designed and simulated InGaN/AlGaN-based near-ultraviolet light-emitting diode (NUV LED) epi-structures to obtain high internal quantum efficiency and low efficiency droop. When the conventional epi-structure of an Al 0:1 Gal 0:9 N last quantum barrier and an Al 0:21 Gal 0:79 N electron blocking layer (EBL) was replaced with a graded last quantum barrier and multi-step EBLs, the NUV LED showed 35 % higher internal quantum efficiency and 25 % more suppression of efficiency droop than the conventional NUV LED. Furthermore, a detailed study of the grading effect of the EBL revealed that 10-step EBLs increase performance when compared to other structures. These results are attributed to the polarization-induced effect, which reduces the electron leakage and increases the hole injection efficiency.

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Performance enhancement of blue light-emitting diodes without an electron-blocking layer by using special designed p-type doped InGaN barriers

Cited by 24 publications

References 28 publications

Elongated nanostructures for radial junction solar cells

Elongated nanostructures for radial junction solar cells

Influence of droplet size on the growth of high-quality self-catalyzed GaAsP nanowires

Design of electron blocking layers for improving internal quantum efficiency of InGaN/AlGaN-based ultraviolet light-emitting diodes

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